1. Field of the Invention
This present invention relates generally to the field of integrated circuit design and, more specifically, to an improved sense amplifier circuit design.
2. Description of the Related Art
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
Memory devices, such as static random access memory (“SRAM”) and dynamic random access memory (“DRAM”), may include arrays of memory cells that each store a bit or element of data. Each data bit or element may represent a logical low (“0”) or a logical high (“1”), which may correspond to a voltage level of a circuit element disposed within the memory cell. As an example, a voltage level close to ground may be representative a logical low or “0” and a voltage level close to a supply voltage for the memory device may be representative of a logical high or “1.” The electrical paths that carry the voltage representing a bit or element of data so that it may be accessed may be referred to as a bitline.
Bitlines may be precharged before the data stored in associated memory cells is accessed. Precharging the bitline may allow faster access to the data stored in the memory cells. In precharging, the voltage level of a bitline is equalized to a voltage in between the voltage levels that correspond to logical lows and logical highs. Thus, when the bitline is accessed and begins to change voltage level to the voltage level corresponding to the data value stored therein, the voltage value on the bitline will only have to transition about half of the range between a logical low and a logical high.
Sense amplifier circuits are coupled to the bitlines to access data stored in a memory cell. A sense amplifier amplifies a signal corresponding to the difference between the voltage level of a bitline and the voltage level to which the bitline is being driven to represent a data value. When bitlines are equalized during precharging, however, the bias voltage presented to a sense amplifier may inhibit the operation of the sense amplifier, making output performance of the sense amplifier slower. Another potential problem is that some bitlines may be too long to be effectively equalized in the time available between memory access cycles. These long lines are typically on the order of 10,000 micrometers (0.01 meters) and are typically global data lines in a memory. This may be true because of the inherent resistor-capacitor (“RC”) delay associated with the long lines.